Spring入門(1)

2019年4月8日

一、ApplicationContext.xml配置及從SpringIOC容器中獲取對象

springIOC容器：創建對象，給對象的屬性賦值

必須jar包：可在mvn倉庫查找

spring-aop: 開發AOP

spring-beans：處理bean

spring-context：處理spring的上下文

spring-core：spring核心

spring-expression：spring表達式

commo-logging.jar：三方提供的日誌jar

創建一個Student類：

public class Student {
    private int stuNo;
    private String stuName;
    private int stuAge;
}

創建ApplicationContext.xml配置文件

<bean

id="student"class="Student">   //此處的class: Student指定一個已經創建的Java類，id：唯一標識此對象

<property name="stuNo"value="2"></property>   //property：屬性

<property name="stuAge"value="21"></property>

<property name="stuName"value="lisi"></property>

</bean>

從springIOC中獲取id爲"student"的student對象

ApplicationContext context=newClassPathXmlApplicationContext("ApplicationContext.xml");

Studentstu=(Student)context.getBean("student");

System.out.println(stu);

二、SpringIOC（是一種超級工廠）

IOC：控制反轉，反轉的是獲取對象的方式，後來方便理解，改名爲DI：依賴注入。

IOC使用實例：

Student類

package com.springTest;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Student {
    private int stuNo;
    private String stuName;
    private int stuAge;

    public int getStuNo() {
        return stuNo;
    }

    public void setStuNo(int stuNo) {
        this.stuNo = stuNo;
    }

    public String getStuName() {
        return stuName;
    }

    public void setStuName(String stuName) {
        this.stuName = stuName;
    }

    public int getStuAge() {
        return stuAge;
    }

    public void setStuAge(int stuAge) {
        this.stuAge = stuAge;
    }

    @Override
    public String toString() {
        return "Student{" +
                "stuNo=" + stuNo +
                ", stuName='" + stuName + '\'' +
                ", stuAge=" + stuAge +
                '}';
    }

    public void learn(String name) {
        ApplicationContext context = new ClassPathXmlApplicationContext("ApplicationContext.xml");
        Course course = (Course)context.getBean(name);
        course.learn();
    }
}

 

Course接口

package com.springTest;

public interface Course {
    void learn();
}

HtmlCourse和JavaCourse

package com.springTest;

public class HtmlCourse implements Course {
    public void learn() {
        System.out.println("learn Html!");
    }
}

package com.springTest;

public class JavaCourse implements Course {
    public void learn() {
        System.out.println("learn Java!");
    }
}

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">

    <bean id="student" class="com.springTest.Student">
        <property name="stuName" value="lisi"></property>
        <property name="stuAge" value="24"></property>
        <property name="stuNo" value="7"></property>
    </bean>
    <bean id="javaCourse" class="com.springTest.JavaCourse">

    </bean>
    <bean id="htmlCourse" class="com.springTest.HtmlCourse"></bean>
</beans>

StudentTest調用

package com.Test;

import com.springTest.Student;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class StudentTest {
    public static void main(String[] args) {
        ApplicationContext context = new ClassPathXmlApplicationContext("ApplicationContext.xml");
        Student stu = (Student)context.getBean("student");
        System.out.println(stu);
        stu.learn("javaCourse");
    }
}